Field of the Invention
This invention generally relates to a bicycle derailleur. More specifically, the present invention relates to a bicycle derailleur having an inner wire guide.
Background Information
A bicycle typically uses a chain drive transmission for transmitting a pedaling force to a rear wheel. The chain drive transmission of a bicycle often uses one or two derailleurs to selectively move a chain from one of a plurality of sprockets to another for changing speeds of the bicycle. A typical derailleur has a base member, a movable member supporting a chain guide and a linkage assembly (e.g., a moving mechanism) coupled between the base member and the movable member so that the chain guide moves laterally relative to the base member. The linkage assembly typically includes a pair of pivotal links pivotally coupled to both the base member and the movable member. A spring typically biases the chain guide to either an innermost or outermost position relative to the sprockets. A Bowden-type control cable is typically coupled between the derailleur and a conventional shift control device. The Bowden-type control cable has an outer casing (sheath) and an inner wire. The inner wire is slidably disposed within the outer casing. Thus, the chain guide of the derailleur can be moved laterally by moving the linkage assembly via the inner wire. Pulling the inner wire moves the movable member and the chain guide against the biasing force of the spring, while releasing the inner wire causes the movable member and the chain guide to move due to the biasing force of the spring. Some rear derailleurs have an inner wire guide disposed on the base member for guiding the inner wire. A metal bush is sometimes fixedly mounted in a through bore of the inner wire guide of the rear derailleur by a swaging process.